1. Field of the Invention
The present invention relates to a resist or etching by-product removing composition and a resist removing method using the same.
2. Description of the Related Art
Semiconductor devices are manufactured via an elaborate series of discrete and sequential processes. After certain of these processes for manufacturing the semiconductor device, e.g., a dry etching process or an ion implantation process, a resist pattern that was used as a mask must be removed. Also, in the case when the resist pattern was misaligned, it must be removed to form a new and correctly aligned resist pattern.
An important criterion of the resist removing process is to completely remove resist and/or etching by-products from the surface of a substrate as fast as possible while not attacking the underlying layers. In general, the typical resist removing process combines a dry stripping step, such as an ashing step, and a wet stripping step using an organic stripper, to remove impurities from the surface of an integrated circuit substrate. Such impurities could be the remaining resist which was not completely removed during the ashing step. Other impurities may comprise the etching by-products generated during etching steps for forming various patterns, for example, single or multiple interconnection patterns formed of tungsten, aluminum, copper, titanium or titanium nitride. Impurities may also be generated during the etching step for forming contact (via) holes exposing the interconnection patterns.
The etching by-products to be removed include organic polymers produced by the reaction of plasma and those components comprising the resist pattern itself, such as carbon (C), hydrogen (H), or oxygen (O), during plasma etching or reactive ion etching (RIE). The etching by-products could also include organometallic polymers produced when interconnection materials are back-sputtered to side walls of the resist pattern and contact holes are formed during an etching or ashing step. The etching by-products could also comprise insulating materials or metal oxides formed when an insulation layer under the interconnection pattern is over-etched and then back-sputtered.
Certain compositions for removing resists or etching by-products are disclosed in U.S. Pat. Nos. 6,242,400 and 6,221,818. The disclosed compositions include a basic amine reducing agent, such as hydroxylamine or monoethanolamine, a polar solvent, and an organic acid such as catechol, as its essential components. However, since the basic amine of these conventional composition is relatively weak in its reducing power, it cannot completely remove etching residues, e.g., a metal oxide or organometallic polymer, that are produced when new interconnection or contact holes are formed. Thus, before the ashing step is performed, a nitric acid pre-treatment step must be carried out.
Since the conventional compositions are comprised largely of organic components and have a high viscosity, etching by-products are not completely removed in the case of rinsing only with deionized water, thereby leaving a residue on the substrate that causes organic contamination.
Also, since the conventional compositions easily corrode an underlying layer exposed to the composition, such as the interconnection layer, the profile of the interconnection layer pattern may be deformed, by undercutting for example. Thus, an additional rinsing step using an alcohol-based rinsing agent such as isopropyl alcohol (IPA) must be performed after the ashing step.
Therefore, since a nitric acid treatment pre-removal step must be performed before the ashing step, and an isopropyl alcohol post-removal treatment step is performed after the ashing step, the resist removal process becomes more complicated and processing time is prolonged, thereby lowering productivity.
Also, since the pre-removal material, e.g., nitric acid, and the post-removal material, e.g., isopropyl alcohol, are further required as well as the resist removal material, the manufacturing costs increase. Moreover, since discrete baths for the pre-removal step and the post-removal step are required, the resist removing apparatus itself becomes more complicated and takes up greater floor space.
In light of the problems and shortcomings of the conventional art, it is an object of the present invention to provide a composition having a superior capability for removing a resist, polymer, organometallic polymer and/or etching by-products, such as metal oxide, while at the same time, the composition does not attack underlying layers exposed to the composition and does not leave residues after a rinsing step.
It is another object of the present invention to provide a method of removing resist or etching by-products using the composition having the capabilities as described above.
To achieve the first object of the present invention, there is provided a resist removing composition comprising alkoxy N-hydroxyalkyl alkanamide, and a swelling agent.
Preferably, the resist removing composition contains at least 10 wt % of alkoxy N-hydroxyalkyl alkanamide and at least 0.01 wt % of the swelling agent. Hydroxylamine salt is preferably used as the swelling agent. Suitable hydroxylamine salts include hydroxylamine sulfate, hydroxylamine hydrochloride, hydroxylamine nitrate, hydroxylamine phosphate, hydroxylamine oxalate, hydroxylamine citrate, and mixtures thereof.
The resist removing composition may further comprise at least one compound selected from the group consisting of a polar material having a dipole moment of 3 or greater, an attack inhibitor, and alkanolamine.
The attack inhibitor effectively suppresses damage to an existing interconnection layer when the interconnection layer is exposed to the resist removing composition. The alkanolamine or polar material having a dipole moment of 3 or greater improves the resist or polymer removing capability.
To achieve another object of the present invention, there is provided a method of removing a resist comprising the steps of providing a substrate having a resist layer formed thereon, and contacting the substrate with a resist removing composition comprising alkoxy N-hydroxyalkyl alkanamide and a swelling agent to remove the resist layer from the substrate.
The composition according to the present invention has a superior capability for removing resist and can effectively remove polymer, organometallic polymer and etching by-products, such as metal oxides. Also, the composition does not leave residues after a rinsing step, and does not attacking underlying layers exposed to the composition.